This invention relates to a rolling bearing for relative lengthwise movement between a shaft and a bearing housing or the like, wherein the housing has a plurality of endless rows of rolling bodies distributed about its circumference. The bearings are held in a cage housing, and the rolling elements, in the rows wherein the balls are loaded, are supported by means of race rails fitted into the bearing housing.
Rolling bearings of this type are known, in which the race rails are provided with convex curvature, in the lengthwise direction of the bearing, on the sides thereof away from the boring of the bearing housing. Such arrangements, as disclosed for example in U.S. Pat. No. 3,545,826 compensate for errors resulting from misalignment of the shaft and boring. Bearings of this type are not suitable for use as components in precision equipment, where stiffness, rigidity and accuracy of the bearings are required, without oscillation of the bearings. Thus, in the above type of bearing, there can be a rocking movement of the bearing housing with respect to the shaft, and such rocking movement results in an unacceptably large yielding or flexing between the shaft and the bearing housing.
In bearings employed for precision machines, another type of bearing must therefore be employed. In such other bearings, which also are known in the state of the art (see DT-PS No. 1,268,442), the radially outer surface of the race rails extend in a staight line in the lengthwise direction of the bearing. This expedient is, of course, suitable in precision machines since there will be essentially no errors resulting from the lack of relative straightness of the shaft relative to the boring of the bearing. As a consequence, in such bearings, it is possible to obtain the necessary stiffness and accuracy, since the race rails are supported along their entire length in the boring of the housing.
These latter rolling bearings have the disadvantage, however, that they are not suitable for use in normal machines having small misalignment between the shaft and the boring, where a certain degree of "rockability" is desired. On the other hand, as discussed above, bearings wherein the race rails have convex curvature in the lengthwise direction in the outer surfaces are not suitable for use in precision equipment, so that differently shaped bearings must be employed for precision equipment. As a consequence, in order to satisfy the different requirements of precision, it is necessary to store a large number of types of bearings, with the consequent increase in the cost of the bearings, as a result of the necessity for storing and producing the differently formed types of bearings.